The present embodiments relate to a wireless transmission from a local coil system to a magnetic resonance system.
A magnetic resonance system includes a tomograph, in which a patient is positioned on a couch in a cylindrical measuring space. A strong magnetic field is provided in the tomograph. The strong magnetic field, on account of the activation of a gradient coil, includes a gradient. The nuclear spin of atoms is adjusted through the magnetic field. A transmitting antenna arrangement (e.g., a whole body transmitting antenna arrangement such as a birdcage antenna) is disposed within the tomograph in order to output magnetic resonance high frequency pulses so as to excite the atoms.
During a magnetic resonance examination, local coils may be used to receive the magnetic resonance response signals in order to receive the pulses during relaxation of the nuclear spin. Different materials exhibit different relaxation behavior, so that conclusions may be drawn as to the interior of the body of the patient on account of the relaxation behavior. The local coils may be combined in assemblies and include receiving antenna elements (e.g., in the form of conductor loops in each case). The received MR response signals may be preamplified in the local coil and routed out of the central region of the magnetic resonance system by way of cables and fed to a screened receiver of an MR signal processing device. The received data is digitalized and further processed. With many examinations, a plurality of such local coils is arranged on the patient in order to cover whole areas of the body of the patient.
The mode of operation of magnetic resonance systems is described, for example, in Imaging Systems for Medical Diagnostics, Amulf Oppelt, Publicis Corporate Publishing, ISBN 3-89578-226-2.
The local coils may be arranged in a local coil mat that is placed above or below the patient body. In addition, specially molded local coil systems such as head coils or neck coils, exist. The signals may be routed from the local coils to an evaluation device of the magnetic resonance system by cables. The cables are undesirable, since the cables may not be easily routed from the patient couch to the evaluation device and are perceived as bothersome by personnel. The patient couch is moved with the patient and the local coil mat, and the cables are consequently loosely routed.
Approaches for the wireless digital transmission of signals between the local coils and the magnetic resonance system are known. The field strength of the transmitter of the local coil is conventionally low, since the local coils may only be supplied with energy in a wireless fashion. In addition, the wireless transmission of signals must not interfere with the imaging. Individual transmitters of a local coil may be shielded on account of position, and the signal transmitted thereby fails to reach a receiver in the magnetic resonance system.
The local coils may be arranged extensively on the patient, and in many cases, the signals of many local coils are to be transmitted from the local coils to the magnetic resonance system at the same time. If a transmitter of a local coil is shielded (e.g., by a medical device or body parts), the image quality is reduced (e.g., the spatial resolution and/or the signal dynamics). The shielding of individual transmitters in the case of a large number of transmitters on a local coil mat with many local coils may be unavoidable and unpredictable. The precise positioning of the limbs of the patient may be no more reliably influenced than that of the medical device.